Internal-combustion heating apparatus



March 11, 1952 R. DUSEK ETAL INTERNAL-COMBUSTION HEATING APPARATUS 6 Sheets-Sheet 1 Filed Sept. 7, 1946 SELECTOR DEF MOIUR k m 3 M m w IIRQI? 2 m a PUMP CONTROL HEAD SAFETY 122 SWITCH Filed Sept. 7. 1946 March 11, 1952 R. DUSEK ETAL 2,588 ;349

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INTERNAL-COMBUSTION HEATING APPARATUS Filed Sept. 7, 1946 6 Sheets-Sheet 5 R. DUSEK ET AL INTERNAL-COMBUSTION HEATING APPARATUS March 11, 1952 6 Sheets-Sheet 6 Filed Sept. 7, 1946 Way Patented Mar. 11, 1952 INTERNAL- COMBUSTION HEATING APPARATUS Robert Dusek, Berwyn, and Stanley J. Budlane, Chicago, Ill., assignors to Motorola, Inc., a C01" poration of Illinois Application September 7, 1946, Serial No. 695,478

combustion heater particularly adaptable for installation in automobiles and other vehicles and for general portable use.

In the prior art various attempts have been made to provide portable internal combustion heaters which are of small, compact and rugged construction so that they will be suitable for installation in automobiles or other vehicles and for general portable use. In these heaters difficulty has been experienced in producing a unit which will operate efficiently over a widerange of heat outputs as is required to heat the passenger compartment of a Vehicle, for example, to the desired temperature in various weather conditions. In general, a heater which is capable of producing the amount of heat required under the very coldest conditions would produce too much heat and/or would operate ineiiiciently in relatively mild weather.

Further difficulties have been encountered in providing a heater which is of very small size so that it may be easily installed or carried and which is of sufficiently rugged and fool-proof construction that dependable operation. will be provided. For safe operation, it is necessary that the heater-structure be so arranged that the combustion air is isolated from the air to be heated so that the poisonous exhaust gases are. carried away from thespace being heated.

A still further problem involved is to provide aheater which will produce a large heat output without requiring a large amount of power for operating the same. In vehicle installationsthe heater must be operated by power obtained from the vehicle battery, and as the avaiiable power in the vehicle battery is almost entirely utilized by other accessories, the power available for operation of the heater very limited. Alsofor portable use, it is desirable that a small amount of external power be required for operation of the heater as in many cases a portable battery will be the only source of electrical power available. Accordingly, an arrangement is necessary whereby the fuel is conditioned for burning, the products of combustion are exhausted, and air to be heated is circulated through the heater by the. use of a minimum amount of power.

It is an object, therefore, of the present invention to provide an improved internal combustion heater which is comp-act and rugged as required for installation in vehicles and for general portable use.

It is another object of this invei'ition to provide an internal combustion heater in which stable and efiicient operation is had at widely varying heat outputs.

A further object of this invention is to provide an internal combustion heater which is arranged for easy installation in Various applications;

A feature of this invention is the provision of a compact and rugged heater unit having a base member on which all ofthe components of the heater are mounted and to which all external connections of the heater are made.

Another feature of this-invention is the provision of an internal combustion automobile heater which is adapted to be mounted either on the cowl or under'the seat of an automobile.

An additional feature or this invention is the provision of a portable internal combustion heater in which a single motor drives air circulating means for providing air for combustion and for circulating air to be-heated through the heater and in which the components of the heater are so arranged that a large amount of air is circulatedby theuse of a small amount of; power;

Still another feature-of this invention is the provision of a burner structure and means for providing preheated air andfuel therefor so that the combustion of the fuel in the burner structure is steady.

Further objects, features and advantages will be apparent from a consideration-of the following description taken in connection with the accompanying drawings inwhich:

Fig. 1 is a perspective'view of the heater in accordance with the invention shown installed on the cowl of an automobile;

Fig. 2- is a cross-sectional view of the heater of Fig. 1;

Fig. 3is a detailed view of thebase plate of the heater:

Fig. 4 is a perspective view illustrating the operating components of the heater;

Fig. 5 is an explodedviewshowingthe manner in which the majorcomponents of the heater are inter-positioned;

Figs. 6 to 9 show details of the burner construction;

Fig. 10 illustrates the control circuit for the heater;

Fig; 11 illustrates the mounting of-' the heater in accordancewith theinvention under the seat of an automoble; and; n

Fig. l2-is a cross-sectional view of the heater and installation ofFig-L 11.

In practicing our invention we provide a selfcontained internal combustion heater including an annular base member on. which all compo nents of the heater are mounted; A motor is positioned ofi-centerof the-base member and a C-shaped combustion chamber is positioned about the motor. The combustion chamber has an opening at one'endin-whiehaburner unitin cluding a pilot burner-and a plurality of additional burning'passages are positioned. The base member has a chamber therein in which combustion air is preheated prior to entry into the burner and" an exhaust chamber having a" fan in the base plate.

therein for causing circulation of air through the combustion chamber. A housing is positioned on the base member and forms a passage about the combustion chamber for air to be heated. A fan is positioned in the housing at the end remote from the base for circulating air through this passage. Fuel feeding means are positioned within the housing between the ends of the combustion chamber for selectably feeding fuel to the burning passages depending upon the heat output required, and a control circuit is provided for automatically controlling the fuel feeding means and for controlling the operation of the heater in general. The heater is suitable for mounting on the cowl or under the seat in an automobile, the only parts differing for the two installations are the mounting means and the vent means for directing the heated air.

Referring now to the drawing, in Fig. l the heater Iii in accordance with the invention is shown mounted on the cowl I l of an automobile under the dash l2. The heater is mounted by a plurality of bolts 13 and includes conduits l4 extending through the fire wall for providing intake and exhaust of combustion air. The heater includes a grille l5 through which air from the passenger compartment of the automobile enters the heater. An annular opening I5 is provided through which the heated air is forced into the passenger compartment. Conduits ll are provided for admitting heated air to the defroster slots l8 normally provided in the dash adjacent the windshield. For the purpose of providing fuel for the heater from the vehicle fuel system, a fuel feed line I9 is provided. A cable makes electrical connections to the heater from the push button control head 2! as will be hereinafter explained. The fuel feed line and cable enter the housing through suitable connectors in a removable portion 22 of the housing which is provided to furnish access to the operating components of the heater as will be presently explained.

For a description of the detailed structure of the heater, reference is made to the Figs. 2, 3, and 5 in which the heater is shown having a base member 23 on which a motor 24 is mounted as by brackets 25. A C-shaped combustion chamber 26 is positioned about the motor as is clearly shown in Figs. 2 and 5. The base member 23 together with the bottom plate 21 secured thereto define a plurality of chambers. An intake air chamber 28 is provided therein into which air enters through opening 29 in the base plate 27. After the air is preheated in the chamber 28 in the base member, it passes through opening therein to the burner housing 3| which is secured to the combustion chamber 26. The base member also has an exhaust chamber 32 therein connected through opening 33 to the exhaust end 34 of the combustion chamber. The combustion chamber 26 issecured to the base member 23 adjacent the openings 35 and 33 therein. Therefore the base member 23 is in heat conducting relationship with the combustion chamber and is heated thereby. The exhaust gases passing through the exhaust chamber 32 also serve to heat the base member. Therefore the base member is held at a relatively high temperature so that the air passing through the intake air chamber 28 therein is substantially preheated. A fan 35 driven by motor 24 is positioned in the chamber 32 to cause a suction therein for exhausting the combustion air through opening 35 7 It is, therefore, seen that a complete passage for combustion air is provided through the intake chamber in the base plate into the burner housing then through the combustion chamber to the exhaustend thereof and into the exhaust chamber in the base plate where the suction fan causes the air to be exhausted from the heater. This passage is shown by the arrows in Fig. 5.

The housing inclosing the heater structure is also secured to the base member 23 and cooperates with the motor 24 and combustion chamber 26 to form a passage for air to be heated between the motor and combustion chamber to the base member and thence between the combustion chamber and the housing to the open end of the housing. Secured to the top of the combustion chamber is a plate 4| on which is supported a cylindrical member 42 and a stationary fan or air guide 43 for directing the air entering the heater. Above the stationary fan 43 is an axial fan 44, also driven by motor 24, for the purpose of drawing air into the heater. The air guide 43 functions to straighten the flow of air entering the heater and reduces the turbulence thereof. .A cover member 45 is provided across the open end of the housing having an opening 46 therein over which grille I5 is placed. The plate 4|, cylindrical member 42 and air guide 43 form an assembly which is supported on casting 26. Openings 41 are provided in plate 4! which register with projections 48 on casting 25 to secure the assembly to the casting (Fig. 2) The cover member may be secured to the plate 4| by any suitable means such as by clips 49 secured to the plate 4|. The air; after passing about the combustion chamber and being heated, leaves the housing through annular opening [5 between the plate M and the housing 4!}.

As is apparent from Figs. 4 and 5, the burner and fuel feeding means are positioned in an arcuate portion between the ends of the combustion chamber 26. Fuel is drawn into the heater by the fuel pump 50 through fuel line 5| and is then supplied through fuel line 52 to pressure regulator 53 and through fuel line 54 to selector 55. The fuel pump and pressure regulator may be of any standard construction, the selector preferably being of the construction disclosed in application Serial No. 644,693 filed February 1, 1946, by Stanley J. Budlane and assigned to the present assignee. The selector provides fuel through fuel lines 56 to a pilot burner and a plurality of additional burning passages as will be later described. The arcuate portion is divided off by the burner housing 3| and by insulating members 51 and 58 as shown in Fig. 5. The insulating member 51 has an opening 59 therein permitting a limited amount of air drawn in by the fan 44 to enter the arcuate portion. The fuel pump, pressure regulator and selector are supported on a bracket 60 which is mounted on the insulating member 58. As described in the above mentioned application, the selector includes a temperature responsive element 6| which controls the supply of fuel to the fuel lines 56. A housing 62 is provided for the temperature responsive element having a neck portion 63 which forms a conduit for directing a portion of the air entering the arcuate portion through opening 59 into the housing so that it comes in contact with the temperature responsive element. A heating coil 64 is provided in the neck portion 53 to se lectively heat the air before contacting the temperature responsive element in a manner to be described. As is apparent from Figs. 1, 2, 4 and 5,

the grille l5 extends back to a defroster housing 05 to which heated air is admitted through the opening I6 at the top of the housing. The housing 65 has opening at therein to which the defroster conduits I! are attached. A slide 01 having an actuating lip 68 is provided for selectively furnishing heated air to the conduits.

Reference is now made to Figs. 6, 7, 8 and 9 in which the details of the burner structure are shown. The burner is provided with a housing 3I having a plurality of openings therein utilized as burning passages, with a cover plate 10 secured thereto to provide a passage H which is adapted to receive combustion air from the base member 23 through the opening 30 therein. The cover plate it has an opening therein in which igniter 12 is mounted and a plurality of additional openings to receive the fuel feeding lines 56. The igniter includes an electrical heating coil l3 having a portion supported by a ceramic cylindrical member it and an exposed portion 75. The igniter is arranged to be connected to a source of electrical power through terminal it, the other end being grounded through the heater housing. The ceramic member Hi of the igniter is surrounded by a pair of spaced cylindrical members 17 and it, the member it having an opening I9 therein through which air and fuel are admitted to the annular passage between the members. A cup-shaped portion St is provided on the cover plate 10 into which fuel is admitted through one of the fuel lines 56 and through which air is admitted from passage "ii. Fuel and air are mixed in the portion 8% and fed to the annular passage in the igniter. This mixture is heated as it traverses the passage causing the fuel to be vaporized and when the mixture reaches the end of the cylindrical member 77 it is ignited by the exposed portion I5 thereof. Due to the current of air through the burner, caused by the suction of fan 35, the flame will move to the ports 8i in the front plate 82 of the burner after combustion has started. The igniter will be de-energized when combustion is started and as the burning does not take place directly at the coil, the coil will not be in danger or" becoming burned out because of the high temperatures.

As shown by the dotted lines in Figs. 7 and 9; additional burners 85 are provided about the pilot burner I2. These additional burners are shown in detail in Fig. 8. The burners 85 include cylindrical ceramic liners 36 positioned in openings 81 in the housing 3| and small tubular members 88 secured to the housing and extending within the ceramic liners. Conduit members 89 connected to the fuel feeding lines 56 provide for the entry of fuel between the tubular members 85 and 88 and. air entering through passage *II enters through tubular member 85% and also through the opening 90 about conduit 89 into the passage between the tubular members 86 and 88. The heat from the pilot burner heats the entire burner housing 3| and, therefore, the air and fuel mixture traversing the burner passages becomes heated. Contact of the fuel with the hot ceramic liners causes vaporization thereof so that a combustible mixture is provided which passes through the ports 9I in the front plate 82. As clearly shown in Figs. 7 and 9, a deflector 92 is provided over the ports SI for the pilot burner. This deflector causes the flame from the pilot burner to circulate to provide efficient burning and has openings 03 therein through which a portion of the flame from the pilot burner may escape. The openings 03 are directed toward the ports 9| for the additional burners so that the flame from the 6 pilot burner ignites the mixture from these burners. Deflector members 94 are provided over the ports 9| so that the name from the burning passages tends to circulate causing all the mixture to become ignited to thereby provide eficient combustion.

The control circuit for the heater is illustrated in Fig. 10. The push button control head 2I is connected to a source of potential I0! such as the storage battery of an automobile and is connected to the operating components of the heater through plug I02 and receptacle Hit. The control head 2I includes five push buttons I04, H35, I08, I07 and I08 which are mechanically interlocked so that when any button is depressed the other push buttons are automatically released. It is noted that the two sets of contacts W0 and 409 associated with push button I34 are adapted to be opened when the push button is depressed and the contacts lit, Iii and H2 associated with push buttons I0 I05 and I 01, respectively, are arranged to be closed when the push buttons are depressed. Although contacts are shown associated with push button W8, these contacts are not used, the only function of push button I08 being to release each of the other push buttons. It is apparent that any standard push button switch assembly may be used in the control panel, the only requirements being that the contacts are sufficiently heavy to carry the currents involved and that one push button opens two sets of contacts and the other push buttons each close the associated contacts. For this reason the mechanical details of the push button switch will not be described. I

When operation of the heater is not desired, the push button Hi4 indicated on the drawing as ch will be depressed and contacts I00 and W9 will be opened. When operation of the heater is desired, any one of the push buttons I05, H36, 601 or 498 will be depressed and the switch contacts asso-- ciated therewith will be closed as well as the switch contacts I06 and I09 as the switch button I0 3 will return to its normal position because of the mechanical interlock. This will apply the potential from the battery IOI through contacts I09 to the conductor 1 I3 which is connected to the terminal marked a of plug I02. When the plug and receptacle are engaged this will energize terminal a of receptacle I03, and make a connection through conductor IM to motor 24 and contact H5 of thermostatic switch H6. The ciosing of contacts I00 will connect conductor H? which energizes a pilot light H8 and terminal 0 of plug H12. Connection is made through terminal c of receptacle I03 to conductor H9 which energizes contact I 20 of thermostatic switch and contact l2I of safety switch I22. The thermostatic switch H6 may be of any standard construction and in addition to the movable contacts H5 and I20 includes stationary contacts 23 and i2 3.

The movable contacts are moved by a suitable temperature responsive element from the position shown, when the element is cold to a position in which the contacts I20 and H3 are broken and the contacts H5 and I24 are engaged when the element is hot. The movable contacts i l5 and I20 are insulated from each other. The thermostatic switch is mounted on the combustion chamber as shown in Fig. 2 adjacent to the burner to be controlled by the temperature thereof.

When the combustion chamber is cold the contacts I20 and I23 will be closed to thereby apply potential to the conductor I25 which energizes igniter l3 and to the conductor I26 which energizes the heating coil I21 of the safety switch I22. The safety switch I22 is arranged so that the contacts I2I and I28 thereof will normally be closed providing a circuit to the pump 50. Although the pump 50 may be of any standard construction, a solenoid operated pump is illustrated having a coil I for driving the same and a pair of contacts I for interrupting the circuit through the solenoid in a well known manner. A condenser I3I is bridged across the contacts I30 to eliminate sparking thereof. After'the heater has been started and the combustion chamber becomes hot, the thermostatic switch IIE will move to the lower position with the contacts I20 and I23 opening to de-energize the igniter l3 and the heating coil I2! of the safety switch.

The safety switch I22 is a slow acting bi-metal switch which requires that the heating coil I21 be energized for a relatively long time before the switch contacts I2I and I28 will open. The purpose of this switch is to stop the pump and thereby stop the flow of fuel to the combustion chamber in the event that ignition of the fuel does not take place. For this reason, the switch must allow sulficient time for combustion to start before opening the contacts I2i and I28.

The contacts H5 and I24 of the thermostatic switch are closed when the combustion chamber is hot providing a parallel circuit for the motor through conductor I32. This conductor is connected through terminal I) of receptacle 403 and terminal 29 of the plug I02 directly to the battery WI and is always energized. This parallel circuit will remain closed after the main switch contacts I09 are opened until the cpmbustion chamber cools off and the thermostatic switch moves to the upper position breaking the contacts i I5 and I24. This arrangement permits the fan to clean out the combustion chamber after combustion ceases to condition the heater for the next use.

In addition to the main operating circuit as above described, an auxiliary circuit is provided through the push button switches I05, E05, I0? and I08 for control of the heating coil associated with selector 55. As previously stated the selector 55 includes a temperature responsive element BI over which air entering the heater is passed to control the supply of fuel to the heater in accordance with the temperature of the incoming air. In order to provide a system whereby the air in the space to be heated is heated to any temperature desired, the heating coil 64 is provided to heat the air in predetermined amounts before it comes in contact with the temperature responsive element to thereby change the temperature range to which the element is responsive. In a specific application the temperature responsive element 05 is arranged to control the flow of fuel to the heater so that the temperature of the air in the space to be heated (the temperature of the air entering the heater) is 80 F. If it is desired that the temperature in the space to be heated be only F., the heating coil 6 can be energized to increase the temperature of the air entering the selector so that the temperature of the air'contacting the temperature responsive element is actually 80 F. This operation is described in detail in application Serial No. 644,693 referred to above. To provide selective heating by the heating coil 64, contacts H0, III and H2 and resistors I33 and I34 are provided. It is apparent that when push button I05 is depressed, the coil lit will be connected through contact IIO directly to the be heated a great amount and the selector to therefore feed a small amount of fuel with the result that the space to be heated will be held at relatively low temperature. Operation of push button I06 will cause the heating coil 64 5 to be connected to the battery IOI through contacts III and resistor I33 causing the current through coil 04 to be less and the heating of the air by the coil to be correspondingly less. This will cause the selector to feed more fuel to provide a higher temperature in the space to be heated. Operation of push button I01 will cause the heating 0011 St to be connected to the battery through contacts H2 in series with resistors I33 and ltd causing a still smaller current through the coil 64 and a correspondingly higher temperature in the space to be heated. When the push button not is operated the heating coil 54 is'completely de-energized and the temperature responsive element Ell is responsive to the temperature for which it is naturally designed.

This will provide a higher temperature in the mobile through the'heater.

space to be heated than when heating coil 64 is energized. It is apparent that by proper design of a temperature responsive element and by proper selection of the coil 64 and resistors I33 and IB E, the push button I05, I06, B07 and H18 can be made to provide any four temperatures desired. These buttons may be marked 50, (ill, ill and indicating that in a particular I application the components are designed to pro-,

vide temperatures of 50, 60, '70 and 80 degrees Fahrenheit. If finer adjustments of temperature are desired, more push buttons and more resistance elements can, of course, be provided.

The operation of the heater as described above will now be set forth. The temperature to which the automobile is to be heated will be chosen in accordance with the desires of the persons in the automobile, the outside temperature generally being an important consideration. Let us assume that a temperature of 70 F. is desired and the push button marked I0 is actuated. This will cause'the motor to operate to circulate air through the combustion chamber as well as circulate air from the auto- The pump will deliver fuel to the 'selector through the pressure regulator and the igniter and heating coil of the safety switch will be energized. The selector will deliver fuel to the pilot burners and may also deliver fuel to the additional burners depending on the temperature of the air entering the heater. The fuel entering the pilot burner is heated by the igniter, mixed with air, and then ignited by the exposed end of the igniter coil. This causes the combustion chamber to become hot and the air being circulated through the heater to be heated. The combustion chamber will soon'reach a sufficiently high temperature to cause the thermostatic switch to operate to cut off the igniter and the heating coil of the safety switch. It is to be noted that if combustion did not take place, the safety switch would, after a predetermined time, out off the fuel pump so that a large amount of fuel would not accumulate in the burner which might cause an explosion on subsequent ignition.

As the air in the automobile is heated, the temperature of the air entering the heater from the automobile will be raised so that the selector will deliver less fuel to the burners. Accordingly, if the automobile was very cold when the heater was started, all the burners would be supplied with fuel immediately and a very large amount of heat would be provided. If the outside temperature is very low, it may be necessary for all the burners to continue operation to heat the automobile to the desired temperature. However, the heat output of the heater is so great that the automobile will usually heat up so that fuel will be supplied to only a part of the burners and perhaps only to the pilot burner. It is pointed out here that fuel is fed to the pilot burner at a fixed rate all the time that the heater is operating but fuel is fed to the additional burners in accordance with the heat output required and varying amounts may be fed to each burner. This is fully explained in application Serial No. 644,693, referred to above. Therefore, the pilot burner always operates while the heater is operating and supplies a small amount of heat for heating the automobile as well as serving to condition and ignite fuel which may be supplied to the other burners. This permits the heat output of the heater to be changed very rapidly and to vary through a wide range.

When the heater is turned off by the push button switch the fuel pump will be de-energized causing combustion to stop but the motor will remain energized through the thermostatic switch as long as the combustion chamber is of such temperature as to hold the switch in the hot position. .This causes the circulation of air to continue through the combustion chamber to clean out any residue of fuel or exhaust gases therein so that the burner will be in proper condition for a subsequent operation. The heater cannot be started until the combustion chamber is cooled off as the igniter will not be energized until the I thermostatic switch is in the cold position. The

continued operation of the pump also circulates air through the heater to thereby lower the temperature of the heater very rapidly. When the combustion chamber has cooled down to a predetermined temperature, the thermostatic switch will operate to disconnect the motor and the heater is completely de-energized.

In the foregoing a heater adapted for mounting on the cowl of an automobile has been described. Referring now to Figs. 11 and 12, it is apparent that the heater is also adaptable for mounting under the seat of an automobile. It is obvious from a comparison of Figs. 2 and 12 that identical structure is used regardless of the position in which the heater is mounted except that the cover member 45 of Fig. 2 is replaced by cover member I59 of Fig. 12. The heater is mounted by securing a mounting plate II to the housing I E3, the mounting plate being secured to the floor boards of the automobile to suspend the heater therefrom. The cover member I53 is secured to the cylindrical member 42 of the heater by clips as indicated at I52. Openings I53 are provided in the cover member I55 opposite the fan 44 to permit air to be drawn into the heater by the fan. As indicated in Fig. 11, the cover member I53 is of generally rectangular shape having open ends adjacent which ducts I54 are positioned to cause the heated air passing between the housing I0 and the plate member 41 of the heater to be conducted both to the front and the rear of the seat of the automobile.

The defroster housing as provided for the cowl mounted heater is eliminated in the under-seat mounting and connection is made to the defroster slots I8 through a flexible conduit I 55. An opening is provided in the housing It) and the flexible conduit I55 is secured thereto so that heated air may enter the conduit. As a relatively long conduit is required, a blower I56 is provided which is installed under the dash I2 of the automobile and has outlets connected to conduits I51 and I58 which are connected to the two defroster slots in the dash. It is not necessary to close the opening in the housing II! when the defroster is not in use as the flexible cable is relatively long and very little heated air will pass therethrough when the blower I56 is not operating.

The control circuit for the heater of Figs. 11 and 12 may be identical to the circuit described with reference to the previous modification except that an additional switch I59 is provided on the control head. This switch may be of any type such as a simple toggle switch and connects the motor I of the defroster blower to the battery IUI. A plug and socket connection IfiI is provided so that the motor may be easily disconnected from the control head. The switch I59 thereby provides control of the defroster at such times as the heater is operating.

As is shown in Figs. 1 and 11, the control head 2| is mounted beneath the dash of an automobile to be in easy access to the operator of the automobile. In such an arrangement the receptacle I93 may be mounted directly on the heater housing and the plug I02 connected through a cable such as illustrated at 2B in Fig. 1 to the control head. This permits the control circuit to be easily disconnected to facilitate servicing of the heater. Such an arrangement is feasible for either type of mounting of the heater. It is obvious that the heater in accordance with the invention is also suitable for portable use in which case the heater unit as shown may be combined in a housing with a fuel tank and a battery, and the control head may be mounted directly on the housing.

From the foregoing description it is apparent that we have provided a heater which is of compact and rugged construction and in which the components are small and relatively simple. The bu ner and fuel feeding structure is such that steady eflicient operation is provided through a wide range of heat outputs. The automatic control system is arranged so that by operating push buttons the space being heated will be automatically brought to the temperature desired regardless of the surrounding conditions.

While we have described what we co'nsi'ie" to be the preferred embo iments, of our invention, it is obvious that various changes and modifications can be made therein with ut departing from the intended scope of the invention as defined in the appended claims.

We claim:

1. Internal combustion heating a paratus comprising a base member for su porting the operating components of said apparatus an including intake and exha st gas chambers therein, said base member being of relativeiy shallow configuration with said exhaust gas chamber being substantially centrally thereof and said intake chamber being elongated and extending about a portion of said exhaust chamber, said chambers having openings therein communicating with the atmosphere, a motor secured to said base member, a C-shaped member having a combustion chamber therein positioned. about said motor and secured to said base member, s id GOmbllstion chamber in heat transfer relation therewith having a combustion opening at one end of its arc and an exhaust opening at the other end of its arc, said exhaust opening being arranged to communicate with said exhaust gas chamber, an exhaust fan within said exhaust chamber driven by said motor for creating a suction at the exhaust opening of said combustion chamber and for exhausting gas from said exhaust chamber, whereby a circumferential flow is induced within said combustion chamber, means secured to said base member for providing a passage for air from said intake air chamber to said combustion chamber, a housing secured to said base member and surrounding the components of. the heating apparatus to form a self-contained assembly, said housing forming a first passage for air about said combustion chamber, a cover for said housing having a central'opening therein, said cover cooperating with said G-shaped member to form a second air passage about said combustion chamber, and a circulating fan disposed Within said central opening and driven by said motor for circulating air to be heated.

2. An internal combustion heating apparatus including in combination, a relatively shallow base member on which the remaining parts of the heating apparatus are mounted, said base member having a cavity therein with dividing Wall means in the cavity forming a substantially central exhaust chamber and an elongated intake chamber about at least a portion of said exhaust chamber and in heat transfer relation therewith, a motor mounted on said base member, a o-shaped, heat transfer member surrounding said motor and having a combustion chamber therein, said heat transfer member being supported on said base member in heat transfer relation therewith whereby the air in said intake chamber is heated by said heat transfer member, said combustion chamber and said base member being so constructed and arranged that a continuous passage is provided through said intake chamber said combustion chamber and said exhaust chamber, and a fan disposed in said base member and driven by said motor for causing a circumferential flow of combustion gases through said continuous passageway.

3. An internal combustion heating apparatus including in combination, a base member having both an elongated intake chamber and an exhaust chamber positioned substantially in the same plane therein, said exhaust chamber being positioned substantially centrally of said base member and said elongated intake chamber extending around at least a portion of said exhaust chamber, a motor mounted on said base member, a C-shaped, heat transfer member surrounding said motor and having a combustion chamber therein, said heat transfer member being supported on said base member in heat transfer relation therewith whereby the air in said intake chamber is heated by said heat transfer member, said combustion chamber and said base member being so constructed and arranged that a continuous passage is provided through said intake chamber said combustion chamber and said exhaust chamber, a fan disposed in said base member and driven by said motor for causing a circumferential flow of combustion gases through said continuous passageway, and means for supplying fuel to be burned to said combustion chamber, said last mentioned means being posed in the open arcuate section defined by the ends of said c-shaped heat transfer member and operatively connected to said combustion chamber.

4. An internal combustion heating apparatus including in combination, a base member having both an elongated intake chamber and an exhaust chamber positioned substantially in the same plane therein, said exhaust chamber being of substantially cylindrical configuration with said elongated intake chamber extending about a portion of the circumference of said exhaust chamber, a motor mounted on said base member, a C-shaped heat transfer member having a combustion chamber therein, said heat transfer member being supported on said base member in heat transfer relation therewith whereby the air in said intake chamber is heated by said heat transfer member, said combustion chamber and said base member being so constructed and arranged that a continuous passage is provided through said intake chamber, said combustion chamber and said exhaust chamber, a fan disposed in said exhaust chamber and driven by said motor for causing a circumferential flow of combustion gases through said continuous passageway, burner means fixed to said C-shaped heat transfer mem er and disposed in the open arcuate section defined by the ends of said 0- shaped member, said burner means being operatively connected to said combustion chamber, fuel supply means disposed in said open arcuate section and connected to said burner means, circulating air temperature control means disposed in said open arcuate section and operatively connected to said burner means, a housing secured to said base member and surrounding the components of the heating apparatus to form a self-contained assembly, said housing forming a first passage for air about said heat transfer member, a cover for said housing having a central opening therein, said cover cooperating with said C-shaped heat transfer member to form a second air passage about said heat transfer member, said first air passage and said second air passage being interconnected to form a continuous circulating air passageway about said heat transfer member, and a circulating fan disposed within said central opening and driven by said motor for circulating air to be heated.

ROBERT DUSEK. STANLEY J. BUDLANE.

REFERENCES CITED The following references are of record in the file of this patent:

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